Correlative Multi-Microscopies Study of Electrodeposited Pt Nano-Assemblies as Precipitation Platforms for Ni(OH)₂

Nanoscience involving nanoparticles (NPs) is a key element in the development of the next generation of efficient and safe systems enabling the conversion or storage of renewable energy. NPs being intrinsically heterogeneous in size, shape or composition, it is of prime importance to develop strategies able to investigate chemical processes at the single entity level or even at the sub-entity level. This will allow identifying structure-activity relationships that is fundamental to predict and control the activity of the NPs. Herein, we have harnessed the controlled monitoring of individual NPs electrodeposited on micrometric conductive surfaces to visualize operando by electrochemical transmission electron microscopy (EC-TEM) and post-mortem high-resolution TEM (HR-TEM) their electrocatalytic activity. It is exemplified herein by tracking the electrodeposition of platinum nano-assemblies (Pt-NA) and their modification by Ni(OH)₂. This electrochemical decoration of Pt nanostructures with metal hydroxides like Ni(OH)₂ is of great interest for the enhancement of hydrogen evolution reaction efficiency in alkaline media.¹ In this sense, we have been able to analyze the morphologies of the electrodeposited Pt-NA <i>post-mortem </i>by HR-TEM depending on the electrodeposition strategy, whereas the precipitation of Ni(OH)₂ was followed <i>operando </i>by EC-TEM. Complementary post-mortem analysis of the nano-assemblies by energy dispersive spectroscopy (EDS) and HR-TEM allowed determining the structure of the bifunctional material. Finally, the reactivity of the Ni(OH)₂/Pt for the hydrogen evolution reaction was investigated by EC-TEM.<br/>References<br/>1. Liu, Q. <i>et al.</i> Optimizing Platinum Location on Nickel Hydroxide Nanosheets to Accelerate the Hydrogen Evolution Reaction. <i>ACS Appl. Mater. Interfaces</i> <b>12</b>, 24683–24692 (2020).